Front wheel suspension system for vehicles having a single front wheel

ABSTRACT

A suspension system for the front wheel of single wheeled vehicles having a single front wheel, such as bicycles, tricycles and motorcycles. The suspension system consists of a frame with a variable arrangement of the steering points using at least one swingable arm, multiple fork joints at least one of which is designed as a two-part fork joint that provides for variable distances between the steering axis, and a telescopic fork connected to the front wheel and which has at least three parts so that the front wheel is guided through the entire system whether partly or fully sprung.

This application is a divisional of U.S. application Ser. No. 10/628,536filed Jul. 28, 2003 which claims the priority of German applications 20211656.5 and 202 11655.7 filed Jul. 29, 2002 and German application 20214757.6 filed Sep. 24, 2002.

BACKGROUND OF THE INVENTION

The invention relates to a front wheel suspension system and method forthe front wheel of vehicles having a single front wheel, such asmotorcycles, tricycles and bicycles.

Most known front-wheel suspension systems for the vehicles having asingle front wheel have a fixed wheel-elevation curve that ispredetermined by the overall vehicle construction. This fixedwheel-elevation curve is a curve along which the front wheel of thevehicle moves throughout the range of the suspension spring system.Thus, the values of the parameters which determine the driving behaviourof such vehicles, such as the steering-angle and trail, are determinedby the construction of the suspension spring system within the range ofthe spring. Usually, the value for trail depends directly andgeometrically on any steering-angle modification, since there is a fixedconnection of the distance of the wheel-guidance means, such as atelescopic fork, to the steering axis.

Thus, for example, in a strong braking action of a motorcycle, thesteering angle becomes steeper and the trail becomes shorter, and themotorcycle is therefore destabilized. In the case of a mountain bikewith a large range of spring, the steering angle can become too steepand the trail too short when the bike is travelling downhill andsimultaneously passing over a bump resulting in the biker having anincreased risk of falling. In such a case, modifications in the settingof the range of spring can usually not achieve any change in thewheel-elevation curve, since the range of spring usually consists onlyof a single spring element which allows only for one elevation movement.Therefore, the telescopic fork is commonly used in front-wheelsuspension systems for bicycles, tricycles and motorcycles, whichsystems consist of a frame and fork joints combined with a telescopicfork.

In the known frames for bicycles and motorcycles which allow for achange of the steering angle, such change is usually achieved byexchanging inserts providing different bearing points of a fixedconnection of the two bearing points in the frame which determine thesteering angle. Due to the necessary assembly work, this is highly timeconsuming. The fork joints for bicycles and motorcycles as known to dateachieve such a possibility of changing the steering-head angle by meansof special bearings. For this purpose, bearings such as single ballbearings or spherical roller bearings are used either in the area of thebearing of the steering axis or in the area of the connection between atleast one fork leg and the fork joint. The thus achieved changes oftrail are obtained by means of the modifications of the steering-headangle under compression, the initial value being determined by a fixedfork off-set between steering axis and fork-leg axis. Due to theirspecial design, the use of the above described bearings is moreexpensive than conventional bearings such as simple roller bearings ortapered roller bearings, while potential changes of trail are mainlycaused by the modification of the steering-head angle.

The known two-part telescopic forks for bicycles and motorcycles onlyprovide for one single movement of the two connection elements over thecourse of compression and rebound of the springs when passing over bumpsor when braking and accelerating. Therefore, in both driving situations,the same geometrical modifications of steering angle and front-wheeltrail are obtained. This modification of frame geometry, whichconstantly and always remains the same even in different drivingsituations, makes an optimisation of driving behaviour adapted to thedriving situation in the respective vehicles impossible.

As illustrated in FIGS. 12 and 13, in this known system, in the reboundposition, a fixed steering angle or rake “R” is predetermined by meansof a frame with a steering head. The trail “T” is also determined bymeans of the fixed distance of the steering axis, in relation to whichthe telescopic fork is usually disposed in parallel by means ofso-called fork joints. Now, in compression to the maximum of the rangeof spring, the values for the steering angle change linearly in relationto the respective range of spring, and, along with the change ofsteering angle, the trail also changes linearly, that is, the steeringangle becomes constantly steeper and the trail becomes constantlyshorter.

There is therefore a need for an improved front wheel suspension systemfor the front wheel of vehicles having a single front wheel, such asmotorcycles, tricycles and bicycles, that will overcome the foregoingdescribed deficiencies of known systems.

SUMMARY OF THE INVENTION

The invention is a front-wheel suspension system for vehicles with onesingle front wheel sprung by a springing system, and comprises a systemwhich by means of different measures of adjustment of the individualcomponents can adapt quickly and easily to the respective field ofapplication and driving situation, especially with regard to the valuesof steering angle and trail over the range of spring. It is mainlyapplicable for bicycles and motorcycles.

The front-wheel suspension system of the invention consists of a framefor bicycles, tricycles and motorcycles which allows for a modificationof the steering angle by shifting the clamping connections of forkjoints on a fork, the steering points of which are connected in at leastone point to a swinging arm through a frame, and at least two forkjoints of which at least one can also be fashioned as a two-part forkjoint that allows for a steering-head angle and trail which isadjustable over the range of spring. In addition, the invention providesa novel spring unit, a telescopic fork. for bicycles and motorcycleswhich allows for a shifting movement of the dipping and slidingconnecting parts which is variable over the course of the range ofspring. On the basis of a suitable setting of the differentpossibilities of relative adjustment of the frame, the fork joints andthe spring units, the system provides many possibilities of adjustment.Especially with regard to the desired wheel-elevation curves, as definedby the parameters of steering angle and trail, adjustment options arenow obtained by reason of the spring units, which differ substantiallyfrom such devices as known to date.

The system according to the invention thus consists of: (1) a frame witha variable arrangement of the steering points using at least oneswingable arm; (2) multiple fork joints at least one of which can bedesigned as a two-part fork joint that provides for variable distancesbetween the steering axis; and (3) a special telescopic fork connectedto the front wheel and which has at least three parts so that the frontwheel is guided through the entire system whether partly or fullysprung.

The invention also includes an embodiment of a frame, the steering-headangle of which is adjustable, and in which the adjustment can beachieved extremely fast by means of a simple shifting movement of aclamping connection of a fork joint.

According to the invention, the fork joint, due to its two-part form,makes a subdivision of the necessary rotating and swivelling movements.Thus, the fork joint on one hand allows for the use of less expensivebearings, and, on the other hand, depending on the particularembodiment, provides for the possibility of an additional change oftrail, since it achieves a change of the fork off-set (that is, of thepivot point of the steering axis in relation to the geometricallyrelevant distance of the fork-leg axis in the fork joint) over theswivel area.

As specially used for motorcycles and bicycles, the construction of thetelescopic fork of the invention consists of slidable connections, whichare slidable into each other and which achieve compression and reboundof the front-wheel assembly during braking or acceleration as well aswhen passing over bumps. Due to the special form of the telescopic forkin at least three-parts, a different suitable relative movement of theindividual connection parts can be achieved over the entire range ofspring, always depending on the setting of the individual spring anddamping rates of the connecting parts with respect to each other. Thus,in the compression and braking processes, an additional modification ofthe front-steering angle can be achieved over the course of the springrange, such as for example in connection with a variably suspendedsteering point, which modification differs from the known steering-anglemodification as achieved by the compression of a conventional telescopicfork.

What is characteristic of the system of the invention is the combinationof at least two spring elements which are adjustable independently fromeach other, the individual ranges of spring of the elements being addedto one overall range of spring for the front wheel to be guided. Thisspecial arrangement therefore provides for variable frame geometrieswith regard to steering angle and trail. At least one of the springelements needs to be attached in between at least one variably hingedsteering point, which is supported by means of a swingable arm by thevehicle frame. Due to this modification of at least one range of spring,the steering axis is defined in relation to the frame by means of therespective arrangement of the at least one swingable arm, thus definingthe corresponding steering angle of the frame. At least one secondspring element is attached either directly to the lower fork jointalone, or within a telescopic fork which has at least a three-part form,the spring element is attached so that it guides the front wheelthroughout its range of spring in relation to at least one swingable armto which the variably hinged steering point is attached. When thissecond spring element compresses, the steering angle of the entirevehicle changes in relation to the level of the roadway as such.

Thus, the driving behaviour of the vehicle can be changed by adjustingthe individual spring elements, which will vary the values of thecritical parameters of steering angle and trail of the front-wheelsuspension system. In other words, the selective arrangement of theindividual spring elements can provide for respectively differentgeometrical modifications of the steering angle and trail which sum upover the overall range of spring of the front-wheel suspension system.

In the case of a direct connection between a wheel-guiding unit such asa telescopic fork, the bearings at the variable steering points have toallow for a rotating as well as a swivelling movement of the steeringpoints through the use of fork joints. The fork joints can be designedas ball-and-socket joint bearings, spherical roller bearings orso-called uni-ball joints. In a preferred embodiment of the system ofthe invention, at least one fork joint, for example the upper one, isdesigned as a two-part fork joint, the bearing of which at the steeringaxis is designed conventionally such that only a steering movement, butno swivelling movement of this first part is possible. The second partof this special fork joint is connected to a spring unit by means ofconventional clamping connections, for example to the upper one of aspecial telescopic fork. The two parts of the fork joint again areconnected to each other by means of a swivel axis. During respectivemovement of at least two parts of a multiple part fork joints systemwhen compressing, the distance between the special telescopic fork andthe steering point of the fork joint designed in two parts is changed.Depending on the particular embodiment of the two-part fork joint, andespecially with respect to the positioning of the swivel axis, anadditional change of trail is obtained within the steering system, whichchange is independent from the change of trail depending on thesteering-angle modification of the overall system in relation to theroadway level of the vehicle.

In another preferred embodiment of the invention, at least one furtherexisting fork joint is designed in a two-part form. However, in thiscase, the swivel axis crosses the conventionally designed bearing at thesteering-axis bearing point.

In a further preferred embodiment at least one further existing forkjoint is designed in a two-part form, but in this case, the swivel axiscrosses the center line of the special telescopic fork, with the bearingat the steering-axis bearing point being fashioned in a conventionalway.

In yet another preferred embodiment the upper spring element is designedas a shock absorber, which bears against the swingable arm and theframe.

In still another embodiment, the system is described in its variationsin combination with three spring elements which are adjustableindependently from each other and which are in connection with eachother by way of two swingable arms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an embodiment of the invention showing theentire front wheel suspension system, FIG. 1 x being an enlarged planview that illustrates a conventional fork joint with a ball-and socketjoint at the steering axis;

FIG. 1 a is a schematic view similar to FIG. 1 but showing in FIG. 1 a 1a two-part fork joint at the upper fork joint and in FIG. 1 a 2 a balland socket joint at the lower fork joint;

FIG. 1 b is a schematic view similar to FIG. 1 a but showing in FIG. 1 b1 a ball and socket joint at the upper fork joint and in FIG. 1 a 2 atwo-part fork joint at the lower fork joint;

FIG. 1 c is a schematic view similar to FIG. 1 a but showing in FIG. 1 c1 a two-part fork joint at the upper fork joint and in FIG. 1 c 2 atwo-part fork joint at the lower fork joint, the swivel axis of whichcrosses the steering point;

FIG. 1 d is a schematic view similar to FIG. 1 c but showing in FIG. 1 d1 a two-part fork joint at the upper fork joint and in FIG. 1 d 2 atwo-part fork joint at the lower fork joint, the swivel axis of whichcrosses the center line of the lower springing unit.

FIG. 2 is a schematic view similar to FIG. 1 but now showing the basicadjustment possibilities of rake and trail of a frame according to theinvention through simply changing the clamping position of the lowerfork joint relative to the telescopic fork;

FIG. 2A is a schematic view similar to FIG. 2 but showing anotherembodiment of the vehicle frame comprised of two movable swinging armsfor steering head adjustments;

FIG. 3 is a plan view of a fork joint or triple clamp mechanism of theinvention shown as used with a fork having two or three sliding wheeltravel units;

FIG. 3 a is an end elevational view of the triple clamp mechanism ofFIG. 3;

FIG. 4 is a schematic illustration of a three part telescopic fork;

FIG. 4A is schematic view similar to FIG. 4 but showing only the lowerelement containing a spring element;

FIG. 4B is a schematic view similar to FIG. 4 but showing anotherembodiment of the fork;

FIG. 4B 1 is an enlarged elevational view further showing the middleelement and the connection of its two parts;

FIG. 4C is a schematic view similar to FIG. 4B but showing anotherembodiment of the fork with only the lower element containing a springelement;

FIG. 4C 1 is an enlarged elevational view further showing the middleelement and the connection of its two parts;

FIG. 4D is a schematic view of a four part fork;

FIG. 4D 1 is an enlarged elevational view further showing the connectionof two parts of two of the elements of the fork of FIG. 4D;

FIG. 4E is a schematic view of another embodiment of a four part forkwith only the lower and the upper element containing a spring element;

FIG. 4E 1 is an enlarged elevational view further showing the connectionof two parts of two of the elements of the fork of FIG. 4E;

FIG. 4F is a schematic view of yet another embodiment of a four partfork with only the lower two elements containing a spring element;

FIG. 4F 1 is an enlarged elevational view further showing the connectionof two parts of two of the elements of the fork of FIG. 4F;

FIG. 4G is a schematic view of yet another embodiment of a four partfork with only the lowest element containing a spring element;

FIG. 4G 1 is an enlarged elevational view further showing the connectionof two parts of two of the elements of the fork of FIG. 4G;

FIG. 5 is a schematic view of the entire front wheel suspension showinguse of the fork of FIG. 4B;

FIG. 5 a is an enlarged elevational view of a portion of FIG. 5 andshowing the lower joint of the fork;

FIG. 6 is a schematic view of the front wheel suspension showing anembodiment using a monoshock suspension and showing use of the fork ofFIG. 4A;

FIG. 7 is a schematic view of the front wheel suspension showing anembodiment using a second swingable arm in the suspension and showinguse of the fork of FIG. 4D;

FIG. 8 is a schematic view of the front wheel suspension showing anembodiment using the fork of FIG. 4 and thus having a rigid element inthe fork between the two swingable arms;

FIG. 9 is a schematic view of the front wheel suspension showing anembodiment using a second swingable arm in the suspension combined witha monoshock suspension unit and showing use of the fork of FIG. 4E;

FIG. 10 is a schematic view of the front wheel suspension showing anembodiment similar to the embodiment of FIG. 9 but showing a variationthereof using a monoshock suspension unit and showing use of the fork ofFIG. 4F;

FIG. 11 is a schematic view of the front wheel suspension showing anembodiment similar to the embodiment of FIGS. 9 and 10 but showing avariation thereof showing two spring elements using a monoshocksuspension unit and showing use of the fork of FIG. 4G;

FIG. 12 is a diagram illustrating the relationship of rake and trail andthe range of spring of a regular fork shown in FIG. 13; and

FIG. 13 is a schematic view of a regular fork illustrating rake andtrail geometrically.

DESCRIPTION OF THE PREFERRED EMBODIMENTS System Design

The drawings illustrate the invention primarily in schematic form.Utilization of the principles of the inventions into the specificconstruction of two-wheeled vehicles would be obvious to persons skilledin the art. As shown in the drawings, the front-wheel suspension systemof the invention consists of a frame 50 for bicycles and motorcyclesthat is supported on ground engaging wheels, a rear wheel 20 and a frontwheel 26. FIG. 1 shows schematically the construction of the entirefront-wheel suspension system which includes a frame 50. This novel typeof frame is shown in FIG. 2 with a variation thereof in FIG. 2A and willbe described in more detail hereinafter. It provides for easy generaladjustment options for the basic steering angle, and thus has a fixedupper steering point 51 and a fixed suspension point 58. At thesuspension point 58, a reversing lever or swingable arm 52 isoperatively connected to a lower steering point 53. The frame 50 isprovided with fork joints 54 and 55 at both steering points 51 and 53,which fork joints are disposed to provide both swayable and rotatablemotion.

In the embodiment of FIG. 1, the bearing of steering points 51 and 53 isprovided by means of a ball-and-socket insert 73, which is maintainedwithin the fork joints 54 and 55 by at least one clamped screwconnection 74 as shown in FIG. 1 x. A spring unit 57 is mounted to thelower fork joint 55 and a spring unit 56 is mounted to the upper forkjoint 54 by means of clamping connection 71 by way of a screw fittingwhich provides at least one screwed connection 72. Depending on therespective embodiment of the system, such as in a three-part telescopicfork with a direct connection for example, the axes of the clampings 71of the spring units extend linearly. The fork joints 54 and 55 areconnected to a special spring system 59 by way of clamping connections,which spring system 59 consists of at least two spring units 56 and 57which are separate from each other. The ranges of spring of these springunits 56 and 57 add up to one overall range of spring of the suspensionsystem. Depending on the adjustment of the individual setting in eachindividual spring unit 56 and 57, the system provides different changesof the values for steering-head angle and trail for the front wheel 26to be guided.

In the embodiment of FIG. 1, the spring system 59 is fashioned as athree-part telescopic fork which will be further described hereinafterwith reference to FIG. 4. In addition, in further preferred embodimentsaccording to FIGS. 1 a-d, a special two-part fork joint is used for thispurpose which provides for a variable trail. This novel two part forkjoint, or sometimes referred to as a triple clamp, is shown in FIGS. 3and 3 a and will be described in more detail hereinafter.

FIG. 1 a (and FIGS. 1 a 1 and 1 a 2) show a detailed representation ofthe use of the two-part fork joint (shown in detail in FIGS. 3 and 3 a)at the top joint 54 and a conventional fork joint with a ball-and socketjoint at the bottom joint 55.

FIG. 1 b shows a detailed representation of the use of the two-part forkjoint at the bottom joint 55 and a conventional fork joint with aball-and-socket joint at the top joint 54.

FIG. 1 c shows a detailed representation of the use of the two-part forkjoint at the top joint 54 and a two-part fork joint at the bottom joint55 in which the swivel axis crosses the steering point.

FIG. 1 d shows a detailed representation of the use of the two-part forkjoint at the top joint 54 and a two-part fork joint at the bottom joint55 in which the swivel axis crosses the center line of the lowerspringing unit.

Frame Design

FIGS. 2 and 2A, show the easy adjustment possibilities for rakeadjustment of the frame 50. The herewith suggested construction of aframe now makes it possible to carry out a modification of the steeringangle in the shortest amount of time. The movable arrangement of atleast one of the steering points 51 or 53 through a sliding arm 52 atframe 50 allows for the change of steering angle by way of a shift inlongitudinal direction of a fork joint 55 comprising a clampingconnection on a fork or telescopic fork 57 which can be provided inseveral different designs. In one embodiment, a bearing point 51 or 53of the steering axis is provided in a movable position. In a furtherembodiment, both bearing points 53 and 53 a of the steering axis arepositioned movably by means of two swinging arms 52 and 52 a.

Thus, as shown in FIG. 2, the bearing points 51 and 53 of the steeringhead which determine the steering head angle are not both affixedpermanently to the frame 50 but at least one of them is affixed with onemoveable steering point 53, e.g., in the axis of the steering head bythe use of the reversing lever or swinging arm 52 which is pivotallyconnected at one end to the fixed front suspension point 58 of the frame50 and at the other end to the steering point 53. The broken lines inFIG. 2 illustrate the change of rake achieved easily by moving thetriple clamps on their clamped connection to any type of fork throughthe swinging movement of the arm 52 and the steering point 53 attachedto it. In the embodiment of FIG. 2A, two bearing or steering points 53and 53 a of steering which determine the steering head angle are notaffixed permanently, but are affixed with two moveable steering points53 and 53 a in the axis of the steering head by the use of two reversinglevers or swinging arms 52 and 52 a. In this case, fork joint 54 onlytakes over a steering function through a fixed steering point 51 a.

The change of the steering angle can be achieved independently of theparticular fork design being used. For example, in one embodiment, thechange of the steering angle is obtained by means of a shift of theclamping connections of a fork joint in an upside-down telescopic fork.In another embodiment, the steering-angle modification is obtained bymeans of a shift of the clamping connections of a fork joint with arigid fork (conventional front fork of a single telescoping design). Inyet another embodiment, the steering-angle modification is obtained by ashift of the clamping connections of a fork joint in a three-parttelescopic fork (double-telescoping of a three piece design). The forkjoint and telescopic fork of the invention as used in these variousembodiments will now be described.

Fork Joint Design

FIGS. 3 and 3 a show the preferred embodiment of the invention of a forkjoint, sometimes referred to as a triple clamp, for the front-wheelsuspension system. A triple clamp is a device especially used formotorcycles and bicycles, and is a mechanical connection between asteering point axis to at least one fork leg. The fork joints forbicycles and motorcycles as known to date achieve such a possibility ofchanging the steering-head angle by means of special bearings. For thispurpose, bearings such as single ball bearings or spherical rollerbearings are used either in the area of the bearing of the steering axisor in the area of the connection between at least one fork leg and thefork joint. The thus achieved changes of trail are obtained by means ofthe modifications of the steering-head angle under compression, theinitial value being determined by a fixed fork off-set between steeringaxis and fork-leg axis. In other words, known existing triple clamps forbicycles and motorcycles primarily allow for a change of trail only by aselection of off-setting devices which change a fixed base value ofdistance (called offset) between the vertical steering axis and thevertical centerline of the forkleg. Therefore, changes of geometrictrail occur only as a function of offset to the steering head angle(rake) of the frame and through wheel travel according to suspensionmovement within telescoping front forks. Due to their special design,the use of the above described bearings is more expensive thanconventional bearings such as simple roller bearings or tapered rollerbearings, while potential changes of trail are mainly caused by themodification of the steering-head angle. In the now obtained specialembodiment of the present construction of a fork joint, such fork joint,due to its two-part form, makes a subdivision of the necessary rotatingand swivelling movements, and thus, on the one hand allows for the useof less expensive bearings, and, on the other hand, depending on therespective embodiment, it provides for the possibility of an additionalchange of trail, since it achieves a change of the fork off-set (thatis, of the pivot point of the steering axis in relation to thegeometrically relevant distance of the fork-leg axis in the fork joint)over the swivel area.

In the embodiment shown in FIGS. 3 and 3 a, a fork joint part member 1,in this case comprising two clamping seats 71 for attaching the forklegs, is connected, for an angle modification to part or member 2 ofsaid fork joint by means of at least one bore 6 and at least one axisbolt 11 on the swivel axis 8. Member 2 comprises one location hole 4 forconnection with a pivoting point of the steering axis as well as atleast one bearing seat 5 for receiving a conventional bearing (here, asan example, a tapered roller bearing) around swivel axis 8.

In parallel position of the axis of fork legs 9 (point 15 geometricallyrelevant) in relation to the steering axis 10 (point 14 supposedpivoting point), the geometrically fork off-set 7 is obtained by addingthe distances of off-set 7′ of the fork joint member 1 of the fork legsin relation to swivel axis 8 plus the off-set 7″ of the fork jointmember 2 of the swivel axis 8 in relation to steering axis 10. Thus, thefork joint of the invention is designed in a two-part form that allowsfor an angle modification between the steering axis and fork-leg axis bymeans of a swivel axis disposed between the two.

Owing to the now possible swivel movement around swivel axis 8, now theresulting distance of the geometrically relevant point 15 in relation to15′ of member 1 of the fork joint changes, such that the geometricallyrelevant portion of the fork offset 7′″ (geometrical connection of point15′ with the center of rotation of the steering axis 14) is obtaineddepending on the respective angle modification between fork-leg axis 9′and steering axis 10. Therefore, the wheel trail of a wheel guided bythe inventive fork joint is changed in addition to the anglemodification of trail obtained by the mere change of the steering-headangle when compression takes place.

In two embodiments, the modification of the angle between the steeringaxis and fork-leg axis can result in the swivel axis 8 crossing eitherthe vertical centreline of the steering axis or the fork leg axis. Whilethese embodiments allow for the above described change of steering-headangle, the effect of additional change of trail however is limited.

In another embodiment, the swivel axis 8 can be disposed at an optionaldistance in between the geometrically relevant connection line of thesteering axis and the resulting fork-leg axis.

In yet other embodiments, the swivel axis 8 can be disposed either: (1)behind the steering axis, at an optional distance outside thegeometrically relevant direct connection line of the steering axis andthe resulting fork-leg axis; or (2) in front of the fork-leg axis, at anoptional distance outside the geometrically relevant direct connectionline of steering axis and the resulting fork-leg axis. Depending on theposition of the swivel axis 8, these embodiments can provide a moreimportant change of trail than the possible embodiments described in thepreceding paragraph.

In yet another embodiment, it possible to use flexible materials for thechange of angle to take place.

The unique fork joint or triple clamp design of the invention allows anadjustment of length of the distance 7′ for adjusting the trail-changingeffect of the fork joint construction by using at least one adjustmentplate 12 and also allows an adjustment of length of the distance 7′″ foradjusting the trail-changing effect of the fork-joint construction byusing at least one adjustment plate 13. Thus, the triple clamp of theinvention divides the necessary rotating and flexing movements to allowfor changes in rake and trail through its design of two jointed parts,and permits the use of inexpensive bearings within. It also permits twostatic changes of geometric steering trail, one according to adjustmentof the steering angle, and the other according to the constant flexiblemovement within the steering angle during flexing of the two joinedparts of the triple clamp.

Telescopic Fork

With reference now to FIGS. 4, and 4A to 4C, the various embodiments ofthe three-part telescopic fork of the invention which allows anadjustable stroke of the moving parts will be described.

Currently known two-part telescopic forks for bicycles and motorcycleshave been created for the vertical movement of compression and reboundonly, without enough consideration for horizontal deflection and theensuing constant alteration of rake and trail geometry. Therefore, theinability to alter the frame geometry during riding motion precludes theoptimization of transgression during certain situations of acceleration,braking, or encounters with road/trail irregularities.

The known two-part telescopic forks for bicycles and motorcycles onlyprovide for one single movement of the two connection elements over thecourse of compression and rebound of the springs when passing over bumpsor when braking and accelerating. Therefore, in both driving situations,the same geometrical modifications of steering angle and front-wheeltrail are obtained. The construction of the present telescopic forkconsists of a slidable connection as specially used for motorcycles andbicycles, which is slidable into each other and which achievescompression and rebound of the front-wheel assembly during braking oracceleration as well as when passing over bumps. Due to the special formin at least three-parts, a different suitable relative movement of theindividual connection parts can be achieved over the entire range ofspring, always depending on the setting of the individual spring anddamping rates of the connecting parts with respect to each other. Thus,in the compression and braking processes, an additional modification ofthe front-steering angle can be achieved over the course of the springrange, such as for example in connection with a variably suspendedsteering point, which modification differs from the known steering-anglemodification as achieved by the compression of a conventional telescopicfork.

During the overall stroke of the telescopic front fork of the invention,there now exists the opportunity to constantly change the front steeringangle of a two-wheeled vehicle, especially when this front fork is usedin conjunction with a fork joint that provides for non-rigid connectionbetween the frame unit and the steering unit of the vehicle.

Moreover, through the design of the three-piece telescopic fork of theinvention, the benefits of flexible steering and frame geometry can beachieved with linked adjustments between the frame and the fork. And theadditional benefit of increased strength is realized due to the overallincreased rigidity of significantly overlapped pieces.

In a general embodiment of FIG. 4, the lower connecting part 21 of thetelescopic fork, which is connected to the guidable front wheel 26 overan axle, is slid into or around the middle connecting element 22, whichin turn is slid into or around the upper connecting element 23. In thisembodiment, the enhanced flexural strength is mainly achieved due to alarger overlapping of the individual connecting elements with eachother.

In a further embodiment, the lower connecting part 21 is supported by aspring 24 which fits closely against the partition wall 27 of connectingelement 22, which connecting element 22 in turn is supported by a spring25 at connection element 23. Since the lower connecting part 21 issupported by the middle connecting element 22 by means of spring 24, thelower connecting part 21 will shift depending on a respective load,while the middle connecting element 22 which is supported by the upperconnecting element 23 also by means of a spring 25, will also shiftaccording to the load. Depending on the adjustment of the individualspring rates in springs 24 and 25, different relative movements of theconnecting elements 21, 22 and 23 to each other are obtained over theentire course of the spring range.

In a special embodiment, the working chambers 28 and 29 of thetelescopic fork are separated from each other not only with respect tospring action but also regarding the damping effect produced bycontrolled damping devices with adjustments for flow rates. Thisprovides for further additional adjustment options. This embodimentprovides two separate working chambers for springing and damping action,which, owing to different adjustments in the respective spring rates anddamping rates, cause a different amount of dipping movement in therespective tubes over the entire range of spring of the telescopic forkto take place In yet another embodiment, instead of conventional springsa pressurized gas is used as a spring.

In a further embodiment shown in FIG. 4A, only the lower element 21 ofthe three-part telescopic fork is designed as a spring element, theupper element 23 being designed only as a guiding element without aspring. In this embodiment, a working chamber 29 is formed between themiddle element 22 and the upper element 23 and is used for dampingpurposes, while a working chamber 28 is formed between the lower element21 and the middle element 22 and is used for both damping and springingaction.

FIG. 4B illustrate another embodiment of a three-part telescopic fork,and FIG. 4C shows a variation of the embodiment of FIG. 4B. In theembodiment according of FIG. 4B, the middle connection element 22A isfashioned in a two-part form. Its parts 22B and 22C are, for example,connected with each other by means of a ball-and-socket joint 80 (SeeFIG. 4B 1). Here, connection element 22B and lower connection element 21form the first spring element 57, while connection element 22C and upperconnection element 23 form the second such spring element 56.

In the embodiment according to FIG. 4C, the middle connection element22A is fashioned in a two-part form. Its parts 22B and 22C are, forexample, connected with each other by means of a ball-and-socket joint80 (See FIG. 4C 1). In this embodiment, connection element 22B and lowerconnection element 21 form a spring unit, and connection element 22C andupper connection element 23 form a slidable guiding unit.

In FIGS. 4D to 4G four embodiments of a four-part telescopic fork aredescribed. These embodiment are used in embodiments of the overallfront-wheel suspension system according to FIGS. 7 to 11.

In the embodiment of FIG. 4D, a four-part telescopic fork is shown inwhich a third connection element 23 a is designed in two parts. Thesesecond and third parts 23 b and 23 c are connected to each other bymeans of a ball-and-socket joint 80 as illustrated in FIG. 4D 1. Part 23b and connection element 22 form a second, middle spring unit,connection element 23 c and the fourth connection element 30 form athird, upper spring unit. Thus, between the lower connecting element 21and the second connection element 22 as well as between the connectingelement 22 and the second part 23 b and also between the third part 23 cand the fourth connecting element 30, three different working chambersare formed for springing and damping effects, which by means ofdifferent adjustment measures of the respective spring rates and dampingrates provide for a different degree of dipping of the respective tubesover the overall range of spring.

In the embodiment according to FIG. 4E, in the working chamber betweenthe connection elements part 23 b and second connection element 22,which are slidable into each other, there is formed only a guiding unitwithout providing any springing effect there being no spring in thisworking chamber,

In the embodiment according to FIG. 4F, the third connection element 23a is comprised of two parts. These second and third parts 23 b and 23 care connected to each other by means of a ball-and-socket joint 80 asillustrated in FIG. 4F 1. The third part 23 c and the fourth connectionelement 30, which are respectively slidable into each other, form aguiding unit only without providing any springing effect.

In the embodiment according FIG. 4G, the second part 23 b and the secondconnection element 22 and the third part 23 c and fourth connectionelement 30, which are slidable respectively into each other, merelyrepresent guiding units without providing any springing effect.

In any of the foregoing embodiments, the springing units can use apressurized gas as a spring, instead of conventional springs.

Combinations of Components of the System

FIG. 5 shows a schematic of an embodiment of the system providing aconnection of the spring units 56 and 57 by way of a ball-and socketjoint 80 (FIG. 5 a) and a telescopic fork arranged according to FIG. 4B.Here, the ball-and-socket joint 80 is mounted inside the spring unit 57and is screwed down with the spring unit 56 by means of the screwfitting 81. Here, it is of no importance that the ball-and-socketconnection 80 is disposed within the fork joint 55. It is crucial,however, that the spring unit 57, which preferably can be a telescopicfork of any type of embodiment, is connected and mechanically fixedly tothe fork joint 55.

In FIG. 6, an embodiment of the system is shown, in which the springunit 56 is a monoshock suspension, which bears against the frame 50through attachment point 56 a and against the swingable arm 52 throughattachment point 56 b. In this case, unit 56 c is a guiding unitconsists of two tubes which are slidable into each other and which donot perform any springing function (e.g., the telescopic fork of FIG.4A). The tubes of guiding unit 56 c serve solely to transmit thesteering forces from the handlebar (not shown) of the vehicle to thefront wheel 26. Here, a direct connection can exist between guiding unit56 c and spring unit 57. The guiding unit 56 c however, can also beconnected to spring unit 57 through a ball-and-socket joint, asdescribed in FIG. 5 a (e.g., the telescopic fork of FIG. 4C).

FIG. 7 shows an embodiment of a spring system 59, which beyond theexisting swingable arm 52 provides a second swingable arm 52 a which ispivotally connected to frame 50 through a suspension point 58 a. At theother end of the swingable arm 52 a the steering point 53 a is provided,which together with steering point 53 of swingable arm 52 now representsthe steering axis of the suspension. Extending over a third fork joint55 a, the overall springing of the spring system 59 is subdivided intothree spring units 56 d, 56 e and 57 and thus allows for additionalwheel elevation curves for the entire front-wheel suspension system withreference to the steering-head angle and the trail. In this embodiment,fork joint 54 only takes over a steering function through steering point51 a. The structure of this fork joint 54 can be designed as describedin FIG. 3. The connection of springing units 56 e and 57 can be carriedout by means of a telescopic fork system as described in FIG. 4D, forexample. Then, the attachment of the spring unit 56 d to spring unit 56e has to correspond to that shown in FIG. 5 a.

In the system as shown in FIG. 8, the unit 56 f is designed rigidlywithout providing for any springing effect. The telescopic fork usedthus corresponds to a three-part telescopic fork such as that shown inthe embodiment of FIG. 4B. In this embodiment, the changes in relationto the steering angle and trail are obtained from an adjustment of thelengths of the swingable arms 52 and 52 a and their suspension points 58and 58 a. The overall range of spring of the front wheel 26 within thefront-wheel suspension system is then defined by means of the resultingranges of spring of the spring units 56 d and 57.

In a variation of the system according to FIG. 9, the spring unit 56 ecan also be designed as a monoshock suspension unit and can bear againstswingable arm 52 through coupling point 56 b and can bear againstswingable arm 52 a through coupling point 56 g. In that case, theconnection parts 23 b and 22 of the telescopic fork merely take onguiding functions within the system, but do not provide for anyspringing effect, as described in the embodiment of FIG. 4E.

In another variation of the system shown in FIG. 10, the spring unit 56d can also be designed as a monoshock suspension unit and can bearagainst swingable arm 52 a through a coupling point 56 g and against theframe 50 through coupling point 56 h. In that case, the connection parts23 c and 30 of the telescopic frame only take on guiding functionswithin the system, but do not provide any springing effect, as describedin the embodiment of FIG. 4F.

In yet another variation of the system shown in FIG. 11, the two springunits 56 d and 56 e also can be designed as monoshock suspension unitsand can bear against swingable arm 52 a through coupling point 56 g andagainst frame 50 through coupling point 56 h as well as againstswingable arm 52 through coupling point 56 b and against swingable arm52 a through coupling point 56 g. In this case, the connecting parts 23c and 30 and connecting parts 23 b and 22 of the telescopic fork onlytake on guiding functions within the system, but do not provide for anyspring effect, as described in the embodiment of FIG. 4G.

SUMMARY

The unique suspension system of the invention for bicycles andmotorcylces allows for an adjustable change of steering angle throughits componensts, especially by dividing the springing movement of afront wheel during suspension action into at least two partly springingmovements. Those are adjustable and at least one of them is located inbetween the steering triple clamp brackets while at least the other onemust be connected below the lower steering triple clamp bracket. Whenthe steering points of said brackets are connected to the frame by aswing arm in at least one location of the frame, an additional andadjustable change of rake occurs. The construction of the frame is asolution for the design of a frame utilizing an adjustable steeringhead, whose adjustment may be performed quickly and easily, throughselective positioning of steering triple clamp brackets. Theconstruction of the frame allows for a change of the steering head anglein a very short time frame. By the use of variable steering points inconjunction with a swing arm to a frame, the steering triple clampbracket is able to be moved along the axial centerline of a fork ortelescopic fork of any design, to achieve a change of steering angle.

The construction of a flexing, two-part triple clamp as described hereinallows for the increased stability of a bicycle or motorcycle. Byallowing articulating movement within the triple clamp, an additionalresultant changing geometric function of trail occurs. When used inconjunction with the steering-to-frame link system, a change ofgeometrically relevant rake is offered, and increased stability of thevehicle is achieved during braking or going over bumps. Additionally,the use of inexpensive bearings is possible, as opposed to bearingscommonly used in the steering components of motorcycles and bicyclesusing conventional one-piece rigid triple clamps allowing these changes.

In addition, the construction of a multiple-piece telescopic fork andits variations as described herein allows for a significant number ofchosen resistances between the movement of its connected parts. Theseinter-related parts, when used in conjunction with linked arms, provideincreased stabilization of steering during acceleration anddeceleration, and increased control during moving encounters with roadirregularities.

The foregoing disclosure of various preferred embodiments is consideredas illustrative only of the principles of the invention. Further, sincenumerous modifications and changes will readily occur to those skilledin the art, it is not desired to limit the invention to the exactconstruction and operation shown and described, and accordingly, allsuitable modifications and equivalents evident to those skilled in theart shall be considered to that fall within the scope of the inventionas defined in the following claims. It is also important that the claimsbe regarded as including such equivalent constructions insofar as theydo not depart from the spirit and scope of the present invention.

1. A front-wheel suspension system for the guidance and springing of thefront wheel of wheeled vehicles having a single front wheel, such asbicycles, tricycles and motorcycles, said suspension system comprising:a frame supported on the vehicle wheels, the frame providing a firstfixed front suspension point, a second fixed front suspension point anda fixed steering point; a swingable arm operatively connected at one endto the fixed front suspension point and providing a variable secondsteering point at the other end of the arm; a second swingable armoperatively connected at one end to the second fixed suspension pointand providing a variable third steering point at the other end of thearm, the second and third steering points defining the steering axis, afork operatively combined with the frame and having at least one forkleg for connection to the front wheel of the vehicle, the fork having alongitudinal axis; a first fork joint operatively connecting the fork tothe fixed steering point; a second fork joint spaced from the first forkjoint along the longitudinal axis of the fork, the second fork jointoperatively connecting the fork to the frame at the second steeringpoint provided by the swingable arm; and a third fork joint spaced fromand between the first and second fork joints and operatively connectingthe fork to the third steering point provided by the second swingablearm, the fixed steering point providing only a steering function; thefork joints connected to the swingable arms being adjustably movablealong the axis of the fork to thereby change the angle of the steeringaxis relative to the frame.
 2. The front wheel suspension system ofclaim 1 in which the fork is a four-part fork, including a lower firstconnection element connected to the front wheel of the vehicle, a secondconnection element, a third connection element and an upper fourthconnection element, the third connection element having two partsconnected to each other by a ball and socket joint, the first connectionelement being slidable relative to the second connection part in a firstworking chamber, the second connection element being slidable relativeto the first part of the third connection in a second working chamber,and the second part of the third connection element being slidablerelative to the upper fourth connection element within a third workingchamber.
 3. The front wheel suspension system of claim 2 in which thefirst connection element is supported by the second connection elementby a spring in the first working chamber, the second connection elementis supported by the first part of the third connection element by aspring in the second working chamber, and the second part of the thirdconnection element is supported by the upper fourth connection elementby a spring in the third working chamber.
 4. The front wheel suspensionsystem of claim 2 in which the second working chamber does not contain aspring but serves only as a guide for the second connection elementwithin the first part of the third connection element for dampingpurposes, and there is a monoshock connected between the first andsecond swingable arms.
 5. The front wheel suspension system of claim 2in which the first connection element is supported by the secondconnection element by a spring in the first working chamber, the secondconnection element is supported by the first part of the thirdconnection element by a spring in the second working chamber, and thesecond part of the third connection element is slidable in the thirdworking chamber within the upper fourth connection element, the thirdworking chamber serving only as a guide for damping purposes, and thereis a monoshock connected between the frame and the second swingable arm.6. The front wheel suspension system of claim 5 in which the secondworking chamber does not contain a spring but serves only as a guide forthe second connection element within the first part of the thirdconnection element for damping purposes, and there is a monoshockconnected between the frame and the second swingable arm and a monoshockconnected between the first and second swingable arms.
 7. A four-parttelescopic fork for use with the front-wheel suspension system for theguidance and springing of the front wheel of wheeled vehicles having asingle front wheel, such as bicycles, tricycles, the telescopic forkcomprising: a lower first connection element connected to the frontwheel of the vehicle; a second connection element; a third connectionelement, the third connection element having two parts connected to eachother by a ball and socket joint; and an upper fourth connectionelement, the first connection element being slidable relative to thesecond connection part in a first working chamber, the second connectionelement being slidable relative to the first part of the thirdconnection in a second working chamber, and the second part of the thirdconnection element being slidable relative to the upper fourthconnection element within a third working chamber.
 8. The four-part forkof claim 7 in which the first connection element is supported by thesecond connection element by a spring in the first working chamber, thesecond connection element is supported by the first part of the thirdconnection element by a spring in the second working chamber, and thesecond part of the third connection element is supported by the upperfourth connection element by a spring in the third working chamber. 9.The four-part fork of claim 7 in which the second working chamber doesnot contain a spring but serves only as a guide for the secondconnection element within the first part of the third connection elementfor damping purposes.
 10. The four-part fork of claim 7 in which thefirst connection element is supported by the second connection elementby a spring in the first working chamber, the second connection elementis supported by the first part of the third connection element by aspring in the second working chamber, and the second part of the thirdconnection element is slidable in the third working chamber within theupper fourth connection element, the third working chamber serving onlyas a guide for damping purposes.
 11. The four part fork of claim 10 inwhich the second working chamber does not contain a spring but servesonly as a guide for the second connection element within the first partof the third connection element for damping purposes.
 12. The four partfork of claim 7 in which a pressurized gas within each of the workingchambers is the spring.
 13. The four part fork of claim 8 in which apressurized gas within each of the working chambers is the spring. 14.The four part fork of claim 9 in which a pressurized gas within each ofthe working chambers is the spring.
 15. The four part fork of claim 10in which a pressurized gas within each of the working chambers is thespring.
 16. The four part fork of claim 11 in which a pressurized gaswithin each of the working chambers is the spring.